The present invention relates in general to scheduling broadcast information and in particular to transmitting electronic television program guide data in a broadcast satellite system.
Television signal distribution systems typically broadcast television signals to individual users or subscribers on a plurality of individual television channels. The channels may be modulated onto one or more carrier frequencies within a discernable frequency band. Some wireless television signal distribution systems use one or more geosynchronous satellites to broadcast a broadband television signal to receiver units within a large geographic area, while other wireless systems are land-based, using one or more transmitters located within smaller geographic areas to broadcast to individual receiver units within those geographic areas.
The receiver unit receives and processes transmitted waveforms. The receiver unit in a satellite systems typically includes a satellite dish connected by a cable to an integrated receiver/decoder unit (IRD). The satellite dish is aimed toward the satellite, and the IRD is connected to the user""s television in a similar fashion to a conventional cable-TV decoder.
Along with the audio and video signals associated with the television channels, the satellite transmits various digital objects such as text and graphics. These objects may be used by the IRD to provide the user with additional information such as an electronic program guide (e.g., a grid of shows and start times). Typically, digital objects used to construct the electronic program guide are serially loaded from the satellite data stream on demand. In other words, when the user enters a command to view the electronic program guide, and further when the user scrolls within the electronic program guide, the receiver unit waits until the next time the required data is broadcast by the satellite and retrieves it.
This method has certain drawbacks. If the electronic program guide data is not repeated by the satellite very frequently, the user must wait when starting up and scrolling through the electronic program guide. If the electronic program guide data is repeated by the satellite more frequently, it consumes more bandwidth. Further, if program information changes while the user is viewing the electronic program guide (e.g., the time a movie starts changes from 8:00 P.M. to 7:00 P.M.), the user may miss the updated information.
In accordance with a first aspect of the invention a method for selectively storing an electronic program guide object in a broadcast system is provided. The method begins by setting a bit in a local mask indicative of a carousel of electronic program guide information. When an object mask associated with the electronic program guide object is acquired, it is compared to the local mask. Subsequently, if the electronic program guide object is associated with the carousel of electronic program guide information, the method stores the electronic program guide object.
In some embodiments, the method further comprises the steps of comparing the object mask to a predefined constant, and storing the electronic program guide object if the object mask is equal to the predefined constant. In such an instance, the predefined constant may be equal to a binary number comprising all ones. In certain embodiments, the method further comprises the steps of receiving a marker, comparing the received marker to a predefined marker; and clearing the bit in the local mask if the received marker is equal to the predefined marker. In some embodiments, the method further comprises the step of determining if a received object is an update object, wherein the step of setting the bit in the local mask is performed in response to determining that the received object is an update object. In certain embodiments, the method further comprises the step of determining if a predefined time period has elapsed since last receiving an update object, wherein the step of setting the bit in the local mask is performed in response to determining that the predefined time period has elapsed. In the preferred embodiment, the broadcast system comprises a direct-to-home satellite system, and the step of comparing the object mask to the local mask comprises a logical AND operation.
In accordance with a further aspect of the invention, an apparatus for selectively storing an electronic program guide object in a satellite television system is provided. The apparatus comprises a satellite signal receiver for receiving the electronic program guide object. The apparatus further comprises a memory for storing the electronic program guide object. Still further, the apparatus comprises a control circuit operatively coupled to the receiver and the memory for determining if an object mask associated with the electronic program guide object is indicative of a predefined carousel of electronic program guide information, the control circuit causing the memory to store the electronic program guide object if the object mask is indicative of the predefined carousel.
In some embodiments, the control circuit is further adapted to compare the object mask to a predefined constant. Subsequently, the control circuit may cause the memory to store the electronic program guide object if the object mask is equal to the predefined constant. In certain embodiments, the control circuit is further adapted to compare a marker received by the satellite signal receiver to a predefined marker, wherein the marker is indicative of a particular point in time associated with the carousel of electronic program guide information. In some embodiments, the control circuit is further adapted to determine if an update object is received by the satellite signal receiver.